Continuity mistake: John is taken down by a trap set by Hansel and puts a big hole in his back. He gets back up and is shot down by the Sheriff. As he is getting up a second time, it shows his back. There is no hole in his back or shirt before the Sheriff finishes him off. It also shows no hole or blood on his back in one shot when he is chasing with the bear trap before he is shot the first time.
Picture added by Quantom X